This invention relates in general to preventing the production of particulate materials through a wellbore traversing an unconsolidated or loosely consolidated subterranean formation and, in particular to, an apparatus and method for obtaining a substantially complete gravel pack within a horizontal open hole production interval without fracturing the formation.
Without limiting the scope of the present invention, its background is described with reference to the production of hydrocarbons through a wellbore traversing an unconsolidated or loosely consolidated formation, as an example.
It is well known in the subterranean well drilling and completion art that particulate materials such as sand may be produced during the production of hydrocarbons from a well traversing an unconsolidated or loosely consolidated subterranean formation. Numerous problems may occur as a result of the production of such particulate. For example, the particulate causes abrasive wear to components within the well, such as tubing, pumps and valves. In addition, the particulate may partially or fully clog the well creating the need for an expensive workover. Also, if the particulate matter is produced to the surface, it must be removed from the hydrocarbon fluids by processing equipment at the surface.
One method for preventing the production of such particulate material to the surface is gravel packing the well adjacent the unconsolidated or loosely consolidated production interval. In a typical gravel pack completion, a sand control screen is lowered into the wellbore on a work string to a position proximate the desired production interval. A fluid slurry including a liquid carrier and a particulate material known as gravel is then pumped down the work string and into the well annulus formed between the sand control screen and the perforated well casing or open hole production zone.
Typically, the liquid carrier is returned to the surface by flowing through the sand control screen and up a wash pipe. The gravel is deposited around the sand control screen to form a gravel pack, which is highly permeable to the flow of hydrocarbon fluids but blocks the flow of the particulate carried in the hydrocarbon fluids. As such, gravel packs can successfully prevent the problems associated with the production of particulate materials from the formation.
It has been found, however, that a complete gravel pack of the desired production interval is difficult to achieve particularly in long production intervals that are inclined, deviated or horizontal. Using conventional gravel packing techniques, the pressure required to pump the fluid slurry to the entire production interval may exceed the fracture pressure of the formation which results in the liquid carrier of the fluid slurry leaking off into the formation.
One technique used to reduce the required pressure for gravel packing a long production interval that is inclined, deviated or horizontal is the alpha-beta gravel packing method. In this method, the gravel packing operation starts with the alpha wave depositing gravel on the low side of the wellbore progressing from the near end to the far end of the production interval. Once the alpha wave has reached the far end, the beta wave phase begins wherein gravel is deposited in the high side of the wellbore, on top of the alpha wave deposition, progressing from the far end to the near end of the production interval.
It has been found, however, that in certain formations with low fracture pressures, such as those found in deep water operations, the pressure required to propagate the beta wave may exceed the fracture pressure of the formation. Therefore a need has arisen for an improved apparatus and method for gravel packing a long production interval that is inclined, deviated or horizontal. A need has also arisen for such an improved apparatus and method that achieve a complete gravel pack of such production intervals and that do not require the pumping of the fluid slurry at a pressure above the fracture pressure of the formation.
The present invention disclosed herein comprises an apparatus and method for gravel packing a long production interval that is inclined, deviated or horizontal. The apparatus and method can achieve a complete gravel pack of such a production interval without pumping of the fluid slurry at a pressure above the fracture pressure of the formation
The apparatus comprises first and second sand control screen assemblies that are connected downhole of a packer assembly. A cross-over assembly that traverses the packer provides a lateral communication path downhole of the packer assembly for the delivery of a gravel packing fluid and a lateral communication path uphole of the packer assembly for the flow of return fluids. A wash pipe assembly, which is in communication with the lateral communication path uphole of the packer assembly, extends into the first and second sand control screen assemblies such that an annulus is formed therebetween. The wash pipe assembly includes a valve that is positioned in a hole location between the first and second sand control screen assemblies. The valve is actuatable from a closed position to an open position when the beta wave of the alpha-beta gravel packing operation is proximate the valve location such that the pressure required to complete the gravel pack will not exceed the fracture pressure of the formation.
The valve may be actuated in response to a differential pressure in the annulus upstream and downstream of the valve. Alternatively, the valve may be actuated in response to either an increase in the density in the wellbore caused by the beta wave gravel deposition or in response to an increase in flow velocity past the valve caused by the beta wave gravel deposition. In the embodiment wherein the valve is actuated by differential pressure, the valve may include an outer housing having an upstream pressure port in fluid communication with the annulus upstream of the valve and a downstream pressure port in fluid communication with the annulus downstream of the valve.
Also in the embodiment wherein the valve is actuated by the differential pressure, the differential pressure may be intensified by placing a restrictor member between the first and second sand control screen assemblies or within the wash pipe assembly or both. The restrictor members are used to reduce the flow area in the annulus adjacent to the restrictor members, thereby increasing the pressure drop in the return fluid traveling therethrough. A restrictor member placed between the first and second sand control screen assemblies may be positioned in the hole location adjacent to the valve. Likewise, a restrictor members placed within the wash pipe assembly may be integral with the valve.
To further intensify the differential pressure, the restrictor members may include turbulizing profiles that create turbulence in the flow of the return fluid in the annulus adjacent to the restrictor members, thereby increasing the pressure drop in the return fluid traveling therethrough. Alternatively, turbulizer members may replace the restrictor members and may be disposed between the first and second sand control screen assemblies or within the wash pipe assembly or both to create turbulence in the flow of the return fluid in the annulus adjacent to the turbulizer members.
The method of the present invention involves positioning first and second sand control screen assemblies within the production interval, disposing a wash pipe assembly within the first and second sand control screen assemblies such that an annulus is formed therebetween, injecting a fluid slurry containing gravel into the production interval exteriorly of the first and second sand control screen assemblies, depositing gravel on a low side of the production interval by propagating an alpha wave from the near end to the far end of the production interval, depositing gravel on a high side of the production interval on top of the gravel on the low side of the production interval by propagating a beta wave from the far end to the near end of the production interval and actuating a valve disposed in the wash pipe between the first and second sand control screen assemblies from a closed position to an open position when the beta wave is proximate the location of the valve.